Almost every shaft out there under 12mm is typically some form of conical taper. At least wood anyway, i guess with cf you could make a really skinny pro taper and not be too whippy. This is why J. Filler went back to wood, he prefers the Z. According to Predator he will go back to Revo when the Z taper version arrives.From my understanding, the Z shafts have a modified conical taper.
The P-Lite pechauer 11.75mm shaft's taper is very close to the Z taper.